NUMERICAL ANALYSIS OF KINETIC ENERGY PROJECTILE SABOT STRUCTURE INFLUENCING THE ARMOUR PENETRATION DEPTH. PART II – ANALYSIS OF PROJECTILE DEVELOPING OPTIONS

Numerical calculations were used to investigate influence of sabot structures of kinetic energy projectiles into the armour penetration depth. Areas of sabot structure for possible optimization and the influence of various sabot materials on the projectile combat efficiency were indicated. The analysis was performed using the finite element method in the Solidworks Simulation environment. It allowed examination of dynamic loads the sabot is subjected to at the time of the shot. Impact of various sabot materials and projectile geometry modifications on the strength of penetrator - sabot connection was investigated. Distributions of dynamical loads for penetrator-sabot connections were simulated and visualised. Calculations on terminal ballistics were performed for some options of the structure. It allowed identification of development trends for this type of ammunition.

High-Velocity Impacts of Pyrophoric Alloy Fragments on Thin Armour Steel Plates

The terminal ballistics effects of Intermetallic Reactive Materials (IRM) fragments have been the object of intense research in recent years. IRM fragments flying at velocities up to 2000 m/s represent a realistic threat in modern warfare scenarios as these materials are substituting conventional solutions in defense applications. The IRM add Impact Induced Energy Release (IIER) to the mechanical interaction with a target. Therefore, the necessity of investigations on IIER to quantify potential threats to existing protection systems. In this study, Mixed Rare Earths (MRE) fragments were used due to the mechanical and pyrophoric affinity with IRM, the commercial availability and cost-effectiveness. High-Velocity Impacts (HVI) of MRE were performed at velocities ranging from 800 to 1600 m/s and recorded using a high-speed camera. 70 MREs cylindrical fragments and 24 steel fragments were shot on armour steel plates with thicknesses ranging from 2 mm to 3 mm. The influence of the impact pitch angle (α) on HVI outcomes was assessed, defining a threshold value at α of 20°. The influence of the failure modes of MRE and steel fragments on the critical impact velocities (CIV) and critical kinetic energy (Ekin crit) was evaluated. An energy-based model was developed and fitted with sufficient accuracy the Normalised EKin crit (E˜kincrit) determined from the experiments. IIER was observed in all the experiments involving MRE. From the analyses, it was observed that the IIER spreads behind the targets with velocities comparable to the residual velocities of plugs and shattered fragment.

Numerical Analysis of Kinetic Energy Projectile Sabot Structure Influencing the Armour Penetration Depth. Part I - Projectile Basic Option

A numerical analysis over influence of kinetic energy projectile sabot structure on the armour depth penetration is presented in the paper. The analysis has identified an influence of sabot different materials into projectile combat performance, and some areas of sabot structure where its shape can be optimised. The finite element method in Solidworks Simulation environment was used in analysis. Due to it the dynamical loads of the sabot at the time of firing could be investi-gated. The influence of sabot different materials and projectile geometry modifications on the strength of penetrator sabot joining was studied. A pattern of dynamical loads for the penetrator sabot joining was simulated and visualised. For selected options of the structure the calculations were performed over the terminal ballistics. It allowed an identification of potential development trends for this brand of ammunition.

Application of a terminal-ballistics model for estimating munition lethal radius on mortar projectiles and rocket warheads

In our previous work, we developed a new terminal-ballistics model developed for artillery high explosive projectiles with natural fragmentation. Lethal radius is here defined as the distance from the detonation point where the effective fragment (80 J) density is 1 frag/m2. In the model, the vertical position of the projectile upon impact is assumed, which means that the lethal radius defines a circular lethal zone (maximum lethal zone of the projectile on the ground). In the research, presented in this paper, we have applied the model to mortar projectiles and rocket warheads, which have different designs compared with classic artillery projectiles. The results from the model, compared to the available experimental results from the quarter-circular arena (used in our country), showed satisfactory accuracy for these types of munitions.

Axial Force Coefficient of APFSDS Projectile

Armor-piercing ammunition is primarily used to combat against heavy armored targets (tanks), but targets can be light armored vehicles, aircraft, warehouse, structures, etc. It has been shown that the most effective type of anti-tank ammunition in the world is the APFSDS ammunition (Armor Piercing Fin Stabilized Discarding Sabot). The APFSDS projectile flies to the target and with his kinetic energy acts on the target, that is, penetrates through armor and disables the tank and his crew. Since the projectile destroys target with his kinetic energy, then it is necessary for the projectile to have the high impact velocity. The decrease in the velocity of a projectile, during flight, is mainly influenced by aerodynamic forces. The most dominant is the axial force due to the laid trajectory of the projectile. By knowing the axial force (axial force coefficient), it is possible to predict the impact velocity of the projectile, by external ballistic calculation, in function of the distance of the target, and to define the maximum effective range from the aspect of terminal ballistics. In this paper two models will be presented for predicting axial force (the axial force coefficient) of an APFSDS projectile after discarding sabot. The first model is defined in STANAG 4655 Ed.1. This model is used to predict the axial force coefficient for all types of conventional projectiles. The second model for predicting the axial force coefficient of an APFSDS projectile, which is presented in the paper, is the CFD-model (Computed Fluid Dynamics).

The penetration of limestone targets by rigid projectiles: Revisited

We reanalyze the results from a set of terminal ballistics tests in which large limestone targets were impacted by similarly shaped rigid projectiles having different sizes. Our first goal is to show that the data in terms of penetration depths as a function of impact velocity can be accounted for by a model in which the limestone’s resistance to penetration is constant throughout the penetration process. It turns out that the actual values of this penetration resistance, as derived from the data, decrease with the projectile’s size. This is a clear manifestation of a scaling issue in the terminal ballistics of the limestone rock. In order to account for this issue we assume that it is closely related to the size effect in the compressive strengths of rock specimens. Finally, we offer a simple procedure by which one can define a surrogate material model for the targets in numerical simulations, in order to predict the penetration depths in limestone, and possibly other rock targets, under both normal and oblique impacts.

New Cartridge Design for Assault Rifle

The article deals with the possible design of a new cartridge for an automatic assault rifle. This hypothetical design is based on the analysis of five automatic assault rifle cartridges which are currently used in armies: 7.62×51 mm NATO, 7.62×39 mm M. 43, 5.56×45 mm NATO and also another two cartridges which are under testing both 6.8×43 mm Rem. SPC and 6.5×38 mm Grendel. The analysis of a new cartridge including internal ballistics, external ballistics, and terminal ballistics energy disposed to the target upon an impact is introduced in the article. The goal was to create a cartridge that would have better ballistic performance than 5.56×45 mm NATO and it would still possess enough accuracy of fire and speed, so that it could dispose at least minimal kinetic energy necessary to incapacitate individuals. Also it is important to maintain the constancy of this effect for the long distance shooting, somewhere around 500 m, during battles in an open area (effective range of 5.56×45 mm automatic assault rifles is normally of about 300 m what only suffices in close quarter battles). To achieve it, the bullet must have the higher sectional density than the 5.56×45 mm cartridge. The sectional density reflects the capability of bullet to penetrate through the human tissue within the requirements of wound ballistics. Based on the analysis, the value of sectional density should be approximately of 0.21 g/mm2. The function of fully automatic firing depends on the size of the recoil energy of a weapon which is also related to the muzzle energy that cannot surpass the amount of 2 500 J. The new cartridge design is based on the 6 mm Scenar bullet (FMJ - Full Metal Jacket bullet with a weight of 5.8 g) made by the Lapua Company. All the ballistic parameters must be within the intervals of strength and construction possibilities of small arms ammunition. To create a possible variation of the mentioned cartridge where its bullet will be powered by a nitrocellulose propellant (originally made in Czech Republic) and a new cartridge case will be created.